File: class.AbsCaptcha.php

<?php
/*
	Changelog
		:: Fri Apr 24, 2009
			I have updated the documentation and the GenerateCaptcha function
			so the session checking is done before generating the captcha image.
*/
/**
* class AbsCaptcha
*
* The AbsCaptcha is a very simple, fully configurable and easy to
* implement class that you can use to generate captcha images.
* While you can change the background color, the text color, the
* width and the height of the image, you cannot change the size of the text.
* It requires the GD library installed and a session started so the
* code from the image can be stored in a session variable.
* This class will regenerate the captcha image for each page request.
*
* Disclaimer:
* This class might not completely stop bots but will definitely
* give them a hard time ;)
*
* @package    AbsCaptcha
* @category   Captcha
* @author     Costin Trifan <costintrifan@yahoo.com>
* @copyright  2009 Costin Trifan
* @licence    http://en.wikipedia.org/wiki/MIT_License   MIT License
* @version    1.0
* 
* Copyright (c) 2009 Costin Trifan <http://june-js.com/>
* 
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
* 
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
final class AbsCaptcha
{
	private function __clone(){}


# PRIVATE PROPERTIES
#==================================

	private
		$sess_name = 'X_CAPTCHA_CODE',	# The name of the session variable that will hold the captcha's generated code
		$save_dir = 'captcha',			# The path to the directory where to store the created captchas(temporary)
		$image_name = 'code_img',		# The name of the captcha image
		$width = 100,					# The width, in pixels, of the captcha image
		$height = 50,					# The height, in pixels, of the captcha image
		$code_length = 6,				# The number of digits and letters to display in the captcha image
		$bgColor = array(0, 0, 0),		# The background color of the captcha image. (r,g,b)
		$fgColor = array(255, 255, 0);	# The image's text color. (r,g,b)
			
		


# PUBLIC METHODS
#==================================

	/**
	* Constructor
	*
	* @param string $captcha_session_name  The name of the session variable that will hold the captcha's generated code. It's important not to use the default assigned name!
	* @param string $save_dir  The path to the directory where to store the created images.
	* @param string $image_name  The name of the image. The image's extension is not required.
	* @param array $image_bg_color  The image's background color.
	* @param array $image_fg_color  The image's text color.
	* @param string $code_length  The number of digits and letters to display in the image.
	* @param string $width  The width, in pixels, of the captcha image.
	* @param string $height  The height, in pixels, of the captcha image.
	*/
	public function __construct( $captcha_session_name='', $save_dir='', $image_name='', $image_bg_color=array(), $image_fg_color=array(), $code_length=NULL, $width=NULL, $height=NULL )
	{
		// GD Library is a MUST !
		if ( !extension_loaded('gd') or !function_exists('gd_info'))
			exit('The <strong>'.__CLASS__.'</strong> class requires the <strong>GD Library</strong> to be able to generate the captcha images!') ;

		$this->SetSessionName($captcha_session_name);
		$this->SetDirectory($save_dir);
		$this->SetImageName($image_name);
		$this->SetImageBgColor($image_bg_color);
		$this->SetImageFgColor($image_fg_color);
		$this->SetCodeLength($code_length);
		$this->SetImageWidth($width);
		$this->SetImageHeight($height);
	}

	/**
	* Create the captcha image.
	* @return boolean
	*/
	public function GenerateCaptcha()
	{
		// update: Fri Apr 24, 2009
		// Makes no sense to generate the image before checking for if the session has been started. (my bad)
		// If the session hasn't been started, the captcha won't work.
		if ( ! isset($_SESSION) )
		exit('Error: The session was not started! The <strong>'.__CLASS__.'</strong> class requires a session to be started in order to function properly!');


		// Create the captcha image
		$captcha = $this->_create_captcha($this->save_dir, $this->image_name, $this->bgColor, $this->width, $this->height);

		// Set the background color for lines
		$line1 		 = @imagecolorallocate($captcha,233,239,239);
		$line2 		 = @imagecolorallocate($captcha, 125, 255, 033);
		$line3 		 = @imagecolorallocate($captcha, 105, 155, 200);
		$line4		 = @imagecolorallocate($captcha, 200, 30, 120);
		$line_yellow = @imagecolorallocate($captcha,255,255,0);
		$line_gray 	 = @imagecolorallocate($captcha, 128, 128, 128);
		$forecolor 	 = @imagecolorallocate($captcha, $this->fgColor[0], $this->fgColor[1], $this->fgColor[2]);
		
		// Draw some lines.
		@imageline($captcha, 0,0,104,129,$line1);
		@imageline($captcha, 10,0,164,129,$line1);
		@imageline($captcha, 50,0,9,139,$line2);
		@imageline($captcha, 70,130,32,32,$line3);
		@imageline($captcha, 80,0,52,52,$line4);
		@imageline($captcha, 90,0,72,72,$line3);
		@imageline($captcha, 84,20,12,72,$line_gray);
		@imageline($captcha, 84,22,13,73,$line_gray);
		@imageline($captcha, 30,0,120,72,$line1);
		@imageline($captcha, 100,122,130,73,$line_gray);
	
		// Generate a random string
		$code = md5(uniqid(rand(), true));
		// cut string to the length of the digits set to be displayed in the image
		$string = strtoupper(substr($code,0,$this->GetCodeLength()));
	
		// Write the string into the image
		@imagestring($captcha, 7, 25, 17, $string, $forecolor);
		
		// Save the new image
		@imagepng($captcha, $this->save_dir.$this->image_name, 9, PNG_ALL_FILTERS);
	
		// Store the code in the SESSION
		//if (isset($_SESSION)) $_SESSION[$this->sess_name] = $string;
		//exit('Error: The session was not started! The <strong>'.__CLASS__.'</strong> class requires a session to be started in order to function properly!');

		// Store the code in the SESSION
		$_SESSION[$this->sess_name] = $string;
	
		return TRUE;
	}


# ACCESSOR/MUTATOR METHODS
#==================================

	/**
	* Set the the name of the session variable that will hold the generated code
	*
	* @param string $sess_name  The name of the session variable that will hold the captcha's generated code
	* @return void
	*/
	public function SetSessionName( $sess_name = '' )
	{
		if ( (strlen(trim($sess_name)) > 0) and !isset($_SESSION[$sess_name]))
			$this->sess_name = $sess_name;
	}

	/**
	* Get the the name of the session variable that holds the generated code
	* @return string
	*/
	public function GetSessionName()
	{
		return $this->sess_name;
	}

	/**
	* Set the background color of the image
	*
	* @param array $image_bg_color  The list of colors(r,g,b) to use to fill the image
	* @return void
	*/
	public function SetImageBgColor( $image_bg_color = array() )
	{
		if (count($image_bg_color) < 1) return;

		if (isset($image_bg_color[0]) and $image_bg_color[0] >= 0)
			$this->bgColor[0] = $image_bg_color[0];
		if (isset($image_bg_color[1]) and $image_bg_color[1] >= 0)
			$this->bgColor[1] = $image_bg_color[1];
		if (isset($image_bg_color[2]) and $image_bg_color[2] >= 0)
			$this->bgColor[2] = $image_bg_color[2];
	}

	/**
	* Set the color of the text that will be displayed in the image
	*
	* @param array $image_fg_color  The list of colors(r,g,b) to use for the text
	* @return void
	*/
	public function SetImageFgColor( $image_fg_color = array() )
	{
		if (count($image_fg_color) < 1) return;

		if (isset($image_fg_color[0]) and $image_fg_color[0] >= 0)
			$this->fgColor[0] = $image_fg_color[0];
		if (isset($image_fg_color[1]) and $image_fg_color[1] >= 0)
			$this->fgColor[1] = $image_fg_color[1];
		if (isset($image_fg_color[2]) and $image_fg_color[2] >= 0)
			$this->fgColor[2] = $image_fg_color[2];
	}

	/**
	* Set the image's code length
	*
	* @param string $length  The number of digits and letters to display in the captcha image 
	* @return void
	*/
	public function SetCodeLength( $length )
	{
		if ( !is_null($length) and $length > 0)
			$this->code_length = $length;
	}

	/**
	* Get the image's code length
	* @return number
	*/
	public function GetCodeLength()
	{
		return $this->code_length;
	}

	/**
	* Set the path to the directory where to save the captcha images
	*
	* @param string $save_dir  The path to the directory where to store the created captchas(temporary)
	* @return void
	*/
	public function SetDirectory( $save_dir = '' )
	{
		if ( ! empty($save_dir))
		{
			if (is_dir($save_dir)) $this->save_dir = $save_dir;
			else {
				if (@mkdir($save_dir)) // try to create the directory
					$this->save_dir = $save_dir;
				else exit('Error: The directory where to store the generated captchas could not be found nor created. Please create it manually!');
			}
		}
	}

	/**
	* Get the path to the directory where to save the captcha image
	* @return string
	*/
	public function GetDirectory()
	{
		return $this->save_dir;
	}

	/**
	* Get the captcha's code stored in the session
	* @return string
	*/
	public function GetCaptchaCode()
	{
		$code = 0;
		if ( isset($_SESSION) and isset($_SESSION[$this->sess_name]))
			$code = $_SESSION[$this->sess_name];
		return $code;
	}

	/**
	* Set the the name and extension of the image
	*
	* @param string $image_name  The name of the captcha image
	* @return void
	*/
	public function SetImageName( $image_name = '' )
	{
		if (strlen(trim($image_name)) > 0)
			$this->image_name = $image_name.'.png';
		else $this->image_name .= '.png';
	}

	/**
	* Get the the name and extension of the image
	* @return string
	*/
	public function GetImageName()
	{
		return $this->image_name;
	}

	/**
	* Set the width of the image
	*
	* @param string $width  In pixels, the width of the captcha image
	* @return void
	*/
	public function SetImageWidth( $width )
	{
		if ( !is_null($width) and $width > 0)
			$this->width = $width;
	}

	/**
	* Get the width of the image
	* @return number
	*/
	public function GetImageWidth()
	{
		return $this->width;
	}

	/**
	* Set the the height of the image
	*
	* @param string $height  In pixels, the height of the captcha image
	* @return void
	*/
	public function SetImageHeight( $height )
	{
		if ( !is_null($height) and $height > 0)
			$this->height = $height;
	}

	/**
	* Get the the height of the image
	* @return number
	*/
	public function GetImageHeight()
	{
		return $this->height;
	}



# PRIVATE (INTERNAL) METHODS
#==================================

	/**
	* Convenient function to create the background support image for captchas
	* @access: internal
	* @return resource  An empty image
	*/
	private function _create_captcha( $save_dir, $image_name, array $bgColor, $width, $height )
	{
		// Create image
		$image = @imagecreatetruecolor($width, $height);

		// Set background color
		$color_background = @imagecolorallocate($image, $bgColor[0], $bgColor[1], $bgColor[2]);

		// Fill the image
		@imagefill($image, 0, 0, $color_background);

		return $image;
	}

}
// >> END
?>